An intensity modulation-direct detection (IM-DD) system is a common optical communication system. The characteristic of this system is to modulate transmitting information on the intensity of light at a transmitting end and to directly perform envelope detection at a receiving end, thereby obtaining transmitted information.
In the implementation of the present invention, the inventors found that a square-law photodetector is usually used at a receiving end in the IM-DD system, whereby a nonlinear operation is introduced, thus resulting in nonlinear cost of the IM-DD system, thereby reducing the performance.
It should be noted that the above introduction to the background art is given for the clear and complete description of the technical solution of the present invention and for the understanding by those skilled in the art. The above technical solutions should not be deemed as being known to those skilled in the art for having been described in the background art of the present invention.